Photodynamic therapy (PDT) is an emerging treatment modality that has shown promise for many types of disease, including cancer. Compared to other common treatment modalities (e.g., radiotherapy and chemotherapy), PDT is minimally invasive, induces low systematic toxicity, and causes little intrinsic or acquired resistance. One downside of PDT, however, is its inability to treat tumors located deep under the skin, a result of short penetration depth of light in tissues. This problem can be partially compensated with advanced light-delivering technologies that allow for illumination of certain internal cavities, such as the bladder, prostate, lung, and esophagus (Agostinis, P., et al. Photodynamic therapy of cancer: an update. CA: a cancer journal for clinicians, 61, 250-281 (2011) and Kostron, H., Methods in molecular biology, 635, 261-280 (2010)). Nonetheless, it is considered challenging or impossible for conventional PDT to treat tumors of large volumes or multiple loci. Recently, there have been exciting developments of novel PDT derivatives, such as two-photon PDT or upconversion nanoparticle-mediated PDT, which aim to minimize tissue interference and improve on penetration depth (Wang, C., et al., Theranostics 3, 317-330 (2013); Gu, Z., et al. Adv Mater., 25, 3758-3779 (2013); Idris, N. M., et al. Nature medicine, 18, 1580-1585 (2012); and Chen, et al., Mat Sci Eng R, 74, 35-69 (2013)). But since light is still employed as the energy source, the efficiency of the treatments may still be surface-weighted.
There is a need for photodynamic therapy systems and methods for treating diseases such as tumors, located deep under the skin, a result of short penetration depth of light in tissues. In accordance, the present disclosure addresses these needs.